Hyundai Sonata 1991 Shop Manual page 176

AUTOMATIC SPEED CONTROL (CRUISE)
TROUBLESHOOTING
BEFORE TROUBLESHOOTING
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The ASC (Automatic speed-control) system performs control func-
tions for the setting or cancellation of the fixed-speed driving
speed based upon the data provided by input signals. As a result.
when the ASC system is canceled, the cause of the cancellation
is memorized in a separate circuit by the ECU, regardless of
whether or not the ASC system condition is normal or abnormal,
thus providing the ECU with the self-diagnosis function by cer-
tain fixed patterns, as well as the function of being able to check
whether or not the ECU's input switches or sensor are normal.
Thus, by effectively using these function, the time required check-
ing and repair can be shortened.
NOTE
When the computer
(ECU)
power supply (ignition switch and
main switch) is switched
OFF,
the memorized diagnosis codes
are erased, and so for this reason the power supply must be
left
ON
until the checking is completed.
Self-diagnosis checking is performed when there has been an
automatic cancellation, without cancel switch operation.
1. The following two methods can be used for checking the diag-
nosis. Note that the diagnosis check connector is located in
the fuse box.
1) If a multi-use tester is used
Connect the multi-use tester's socket and connector to
the cigarette lighter socket and the self-diagnosis check
connector, and set the tester.
Use the tester according to its operation instructions; dis-
play the diagnosis code number and then check.
SELF-DIAGNOSIS CHECKING
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